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    find values of theta in interval 0< (or qual toZ) theta < 360

    cosi (theata +75) = 0


    thanks!
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    you do inverse cos so

    cos-1 (0) = ???? ( u get two ansers)

    (To get the other answer you must either look on the cast diagram or the cosine curve.)

    (theta + 75) = ?????(1) and ?????(2)

    theta = ????(1) - 75 and ????(2) - 75

    Keeping in mind the theta values must lie in the range 0 - 360
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    this is what i did: cosi 0 = 90 or 270

    270- 75 = 195
    90-75 = 15

    but the markscheme (setB paper 1) says: theatra = 225 or 345
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    Well if you quote the question correctly the markscheme is wrong.

    cos(225 + 75 ) = cos(300) which is not 0.
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    the question must have said:

    cosi (theata +75) =1/2 then or the mark scheme is wrong.
 
 
 
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Updated: June 19, 2005
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